A practical guide to wiring the Festo VADMI compact vacuum generator with a vacuum sensor to a PLC. The wire assignment is verified by physical measurement on the component itself, not just read from the datasheet. Components: VADMI-140-LS-P (171059), 2× MSOEB-3-24V DC coil (1928168), vacuum sensor 379329 (PNP, 0…−1 bar), Festo connecting cable 396054. Wire assignment blue = 0 V (common for coils and sensor) brown = +24 V → VACUUM coil; also powers the sensor white = +24 V → BLOW-OFF coil black = sensor signal (vacuum reached) → PLC input How it works The ejector has two independent coils. One switches vacuum (picking up the part), the other a short blow-off pulse to release the part from the suction cup. Both share 0 V (blue) and are switched by positive +24 V (PNP logic). Sensor 379329 is internally powered from the vacuum branch (brown), so its signal on the black wire is valid only while vacuum is on. When vacuum is off, the black wire goes idle — this is normal, not a fault. Operating sequence Vacuum ON (brown) → vacuum builds up. Sensor sends "part gripped" on the black wire → PLC continues. Move the part. Vacuum OFF (brown). Short blow-off pulse (white, ~0.1–0.3 s) → part is released. Blow-off OFF. Warning: never switch vacuum and blow-off at the same time. Verification by measurement With no power or pressure, measure resistance. A ~384 Ω pair is a coil. The wire reading ~384 Ω against two different wires is the common 0 V. Briefly apply 24 V to a coil wire and watch whether vacuum or blow-off actuates. The manual override physically confirms which coil is the vacuum one. Sensor test: apply 24 V to the vacuum wire and watch the signal wire.